I have been playing Tokyo Twilight Busters while writing an English guide, and I came across this part of the game when opening up the basement in the scenario "禁断のアトリエ". It asks for a 5 number sequence and it doesnt seem story related at all, I'm pretty sure its copy protection.
Japanese guides online for both the PC98 and DS versions dont mention this code at all.
Its wierd to put copy protection this far into the game. The game is unbelievably difficult and just getting to this point on my own with slight help from various guides took me like 15-20 hours haha.
If I knew about this I woulda tried to buy the game sooner, I've had my eye on YAJ for years now for a complete copy.
Anyone have a physical copy of the game to see if the code is in there? It would be massively appreciated.